Disk drive including I-regions having configurable final logical block addresses

ABSTRACT

A disk drive includes a controller and at least one disk, which may include a first I-region, a second I-region, and an E-region. The first and second I-region may have a first final logical block address (LBA) and a second final LBA, respectively. The controller may be configured to cause information to be written to the first I-region and the second I-region using a first type and a second type of magnetic recording, respectively. The controller also may be configured to set at least one of the first final LBA or the second final LBA to a final LBA value higher than the at least one of the first final LBA or the second final LBA, respectively, after writing user data to at least a portion of the first I-region or the second I-region and without removing the user data.

TECHNICAL FIELD

Various embodiments described herein relate to a method and apparatusfor actively writing information representing data to a mixed mode diskdrive having idle time and an expandable I-region and E-region.

BACKGROUND

A disk drive is an information storage device. The most basic parts of adisk drive are at least one information storage disk that is rotated, anactuator that moves a slider carrying one or more transducers to variouslocations over the disk, and electrical circuitry that is used to writeand read data to and from the disk. The one or more information storagedisks are clamped to a rotating spindle. More specifically, storing dataincludes writing information representing the data to portions of trackson a disk. The transducer includes two separate devices—a writetransducer that writes information representing data to the disk and aread transducer or sensor that reads information from the disk.

Storing data includes writing information representing the data to thedisk. Conventional disk drives with magnetic media organize data inconcentric tracks. There is a constant goal in these storage devices tostore increased amounts of data. Two ways of increasing the storagecapacity of these storage devices include increasing the bit density,which means reducing the spacing between individual bits along thecircumference of a concentric track or a substantially concentric track.The tracks can also be written as spirals in some applications. The bitdensity can be increased along the spiral path.

Another way to increase the capacity is to increase the track density.This involves writing the tracks more closely together.

Of course different writing techniques can be used to produce driveswith more capacity. In the past, magnetic transitions were writtenlongitudinally. Most recently, capacity increases have been achieved bywriting the magnetic transitions perpendicular to the major surface ofthe disk. Different types of perpendicular magnetic recording have beendeveloped. In the past, disk drives use a single type of perpendicularrecording. The capacity of these disk drives is determined at the timeof manufacture and generally remains static or fixed. Capacities of thedisk drives do not increase. Sometimes the data capacities of the diskdrives decrease.

SUMMARY OF THE INVENTION

A disk drive is written with at least two types of perpendicularmagnetic recording. For example, the disk drive can have two regions fordata and in one region, the information representing data can be writtenusing indirect perpendicular recording, and can be written in anotherregion using shingled magnetic recording. In addition, the disk driveincludes hardware for determining if it is operating in favorableconditions and for increasing the data capacity.

A disk drive according to the present disclosure includes at least onedisk with at least two major disk surfaces comprising a first I-regionhaving a first maximum logical block address, a second I-region having asecond maximum logical block address, and an E-region. In oneembodiment, information representing data is initially written to theE-region. The information representing data is reread and written to atleast one of the first I-region or the second I-region. In anotherembodiment, the information representing data is written directly andsequentially into the first I-region and the second I-region. Theinformation written to the first I-region is written using a firstmethod and the information written to the second I-region is writtenusing a second method.

The disk drive includes physical block addresses where data is stored.The physical block address relates to the actual physical address of aset of data. The disk drive also includes logical block addresses whichare mapped to physical block addresses. At least one of the firstend/final logical block address or the second end/final logical blockaddress is reset to a value higher than the at least one of the firstend/final logical block address or the second end/final logical blockaddress after writing to at least a portion of the first I-region or thesecond I-region, respectively. In other words, the regions can bewritten so as to hold more data than originally set for at the time ofmanufacture. In many instances, the data capacity is designed to a lessthan perfect case scenario. The conditions where a disk drive operatescan, many times, be more favorable than the design point. When afavorable condition or conditions are detected, the write operations canbe controlled to write data that will result in increased capacity.

The disk drive further includes a controller for determining theincrease in capacity for the respective I-region. The controllermonitors the disk drive for conditions favorable to writing at anincreased capacity. The controller also determines the write method touse to increase capacity. The controller also determines when the driveis likely to be idle for a period of time so that it can perform writesthat may take longer to complete during the idle times. In someembodiments, a disk drive has a plurality of disks which have two majorsurfaces for storing information for storing data.

A computer system includes a host and a disk drive apparatuscommunicatively coupled to the host. The disk drive includes at leastone disk having two major surfaces divided into a plurality of regions.Each region includes a start logical block address and a maximum logicalblock address wherein the host sets a region as allocated and requeststhe last logical block address for the region, the host frees theallocation up to the last logical block address in response to the diskdrive returning the last logical block address, and after the lastlogical block address is consumed, the host requests the last logicalblock address again. The host, in response to receiving an increasedmaximum logical block address indication for the region, frees the spaceassociated with the region between the increased maximum logical blockaddress and the previous maximum logical block address. It should beunderstood that the disk drive does not necessarily have to indicate tothe host that there is more space available in a region. In oneembodiment, for example, the disk drive can reallocate additionalphysical block addresses to an E-region. The extra physical blockaddresses can be designated as an additional E-region or can bedesignated to hold a copy of data for use in revolutions per minute(RPM) multiplication. RPM multiplication is a scheme for makinginformation representing data available faster by decreasing the seektime to get to the data within the drive.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 is a schematic top view of a disk drive, according to anembodiment of the invention.

FIG. 2 is a schematic diagram illustrating an example of a plurality ofregions on the surface or surfaces of one or more disks in a disk drive,according to an example embodiment.

FIG. 3 is a schematic diagram of an example error correction unit,according to an example embodiment.

FIG. 4 is a flow diagram of a method for increasing the data capacity ofa disk drive from the factory settings for data capacity, according toan example embodiment.

FIG. 5 is a flow diagram of another method for increasing the datacapacity of a disk drive from the factory settings for data capacity,according to an example embodiment.

FIG. 6 is a schematic diagram showing physical regions of a disk drivethat have a plurality of tracks that include a plurality of physicalblock addresses, and which include a plurality of groupings of logicalblock addresses which correspond to the regions, according to an exampleembodiment.

FIG. 7 A shows a disk of a disk drive, according to still anotherexample embodiment.

FIG. 7B shows a disk of a disk drive that has rotational copies ofinformation representing data, according to an example embodiment of RPMmultiplication.

FIG. 7C shows a disk of a disk drive that has another embodiment ofrotational copies of information representing data, according to anotherexample embodiment of RPM multiplication.

FIG. 8 is a schematic diagram showing a disk that uses banded recording,according to an example embodiment.

FIG. 9 is a flow diagram of a method for decreasing far trackinterference on a disk drive, according to an example embodiment.

FIG. 10 is a flow diagram of a method for writing information to amagnetizable disk surface on a disk drive, according to an exampleembodiment.

FIG. 11 is a flow diagram of a method for moving unreadable blocks ofinformation representing data to another readable area on the disk,according to an example embodiment.

FIG. 12 is a schematic diagram showing the transfer of data from onephysical block address or one set of physical block addresses to anotherphysical block address or another set of physical block addresses,according to an example embodiment.

FIG. 13 is a flow diagram of a method for writing information to amagnetizable disk surface on a disk drive, according to an exampleembodiment.

FIG. 14 is a flow diagram of a method for varying the capacity of a diskdrive, according to another example embodiment.

FIG. 15 is a schematic diagram of a physical region of a disk drive anda logical capacity of the physical region at two times T1, T2, accordingto an example embodiment.

DETAILED DESCRIPTION

In the following paper, numerous specific details are set forth toprovide a thorough understanding of the concepts underlying thedescribed embodiments. It will be apparent, however, to one skilled inthe art that the described embodiments may be practiced without some orall of these specific details. In other instances, well known processsteps have not been described in detail in order to avoid unnecessarilyobscuring the underlying concepts.

In general, this disclosure describes techniques for writing data to astorage medium. In particular, this disclosure describes a disk withdifferent regions. In the different regions, different recordingtechnologies are used. The disk drive also can include a write bufferarea called an E-region. Techniques described in this disclosure areused to write data to the disk in the various regions using severaldifferent write technologies. In addition, the regions can be written atvarious capacities based on a determination of a favorable operatingenvironment. This produces a disk drive having a variable capacity. Thedata capacity of one or more regions of the disk or disks can beincreased using one or more of writing techniques described or bychanging the parameters of the writing techniques. The writingtechniques are changed on the fly or in the field after performanceindicators are used to determine if the capacity can be increased.

FIG. 1 is a schematic diagram illustrating an example hard disk drivethat utilizes the techniques described in this disclosure. Hard diskdrive 100, in this example, is operably coupled to a host device as aninternal or an external data storage device. The disk drive 100 can bein a stand alone personal computer (PC) or can be part of a bank of diskdrives used to store data, such as in a data warehouse. A host devicemay include, for example, a laptop or desktop computer or a similardevice. The host device can also be a server. Hard disk drive 100,includes data recording disk or medium 102, spindle assembly 104, slider106, actuator arm 108, voice coil motor assembly 110, a voice coil motor(“VCM”) and motor predriver 112, spindle motor driver 114, preamplifier116, read/write data channel unit 118, processing unit 120, data bufferrandom access memory (RAM) 132, boot flash 134, host interface unit 136,and vibration measurement unit 138. Further, processing unit 120includes hard disk controller 122, interface processor 124, servoprocessor 126, instruction static random access memory (SRAM) 128, anddata SRAM 130. It should be noted that although example hard disk drive100 is illustrated as having distinct functional blocks, such anillustration is for descriptive purposes and does not limit hard diskdrive 100 to a particular hardware architecture. In a similar manner,processing unit 120 should not be limited to a particular hardwarearchitecture based on the example illustrated in FIG. 1. Functions ofhard disk drive 100 may be realized using any combination of hardware,firmware and/or software implementations.

Disk 102 is coupled to spindle assembly 104 and rotates in direction Dabout a fixed axis of rotation. Disk 102 may be rotated at a constant orvarying rate. Typical rates of rotation range from less than 3,600 tomore than 15,000 revolutions per minute. However, disk 102 may berotated at higher or lower rates and the rate of rotation may bedetermined based on a magnetic recording technique. Spindle assembly 104includes a spindle and a motor and is coupled to spindle motor driver114. Spindle motor driver 114 provides an electrical signal to spindleassembly 104 and the rate at which the spindle rotates, and thereby disk102, may be proportional to the voltage or current of the electricalsignal. Spindle motor driver 114 is coupled to a VCM and motor predriver112. The spindle motor is typically housed within the spindle assembly104. The spindle motor and VCM and motor predriver 112 are configured touse feedback techniques to insure disk 102 rotates as a desired rate.For example, VCM and motor predriver 112 may be configured to receivecurrent and/or voltage signals from the motor for example and adjust theelectrical signal provided to spindle motor driver 114 using feedbackcircuits. The feedback circuits compare a desired rotational position tothe actual radial position. In some embodiments, servo wedges associatedwith embedded servo are used to provide radial position information.

As illustrated in FIG. 1, VCM and motor predriver 112 is also coupled tovoice coil motor assembly 110. In addition to providing an electricalsignal to spindle motor driver 114, VCM and motor predriver 112 is alsoconfigured to provide an electrical signal to voice coil motor assembly110. Voice coil motor assembly 110 is operably coupled to actuator arm108 such that actuator arm 108 pivots based on the current or voltage ofthe electrical signal received from VCM and motor predriver 112. Asillustrated in FIG. 1, slider 106 is coupled to actuator arm 108. Thus,VCM and motor predriver 112 adjusts the position of slider 106 withrespect to disk 102. VCM and motor predriver 112 may use feedbacktechniques to ensure slider 106 maintains a desired position withrespect to disk 102. In one example, VCM and motor predriver 112includes an analog-to-digital converter to monitor electromagneticfields and current from voice coil motor assembly 110.

Slider 106 is configured to read and write data to disk 102 according toa magnetic recording technique, for example, any of the example magneticrecording techniques described herein. Slider 106 includes a read headand a write head corresponding to each of a plurality of disks includedas part of disk 102. Further, slider 106 may include one or more readand write heads for each disk. For example, each disk in a stack ofdisks includes two major surfaces to which data can be stored. In oneembodiment, there is a slider 106 positioned in transducing relationshipwith one major surface and another slider 106 positioned in transducingrelationship with the other major surface of each disk in the diskstack. Slider 106 is coupled to preamplifier 116. Preamplifier 116 mayalso be referred to as arm electronics (AE). Preamplifier 116 isconfigured to select a correct head from a plurality of heads for aparticular read or write operation. Preamplifier 116 is configured todrive a write head of slider 106 with a write current during a writeoperation. Further, preamplifier 116 is configured to amplify readsignals from slider 106, during a read operation using a programmablehead bias current. Preamplifier 116 may also be configured to detecterrors during each of the read and write operations. Preamplifier 116may include a signal adaptive filter (SAP) for thermal asperity (TA)recovery during a read operation.

Preamplifier 116 receives data to be written to disk 102 from read/writedata channel unit 118. Further, preamplifier 116 provides data read fromdisk 102 to read/write data channel unit 118. Data may originate from ahost device and may be communicated to read/write data channel unit 118via host interface unit 136 and processing unit 120. Host interface unit136 provides a connection between hard disk drive 100 and a host device.Host interface unit 136 may operate according to a physical and logicalcharacteristic s defined according to a computer bus interface. Examplestandardized interfaces include ATA (IDE, EIDE, ATAPI, UltraDMA, SATA),SCSI (Parallel SCSI, SAS), Fibre Channel, and PCie (with SOP or NVMe).

As illustrated in FIG. 1, processing unit 120 includes hard diskcontroller 122, interface processor 124, servo processor 126,instruction SRAM 128, and data SRAM 130. Instruction SRAM 128 may storea set of operation instructions for processing unit 120. In oneembodiment, instructions are loaded to instruction SRAM 128 from bootflash 134 when hard disk drive 100 is powered on. Data SRAM 130 and databuffer RAM 132, which is coupled to processing unit 120, are configuredto buffer blocks of data during read and write operations. For example,blocks of data received from host interface unit 136 may be sequentiallystored to data SRAM 130 and data buffer RAM 132 before the data blocksare written to disk 102. It should be noted that although instructionSRAM 128, data SRAM 130, data buffer RAM 132, and boot flash 134 areillustrated as distinct memory units, the functions of instruction SRAM128, data SRAM 130, data buffer RAM 132, and boot flash 134 may beimplemented according to other types of memory architectures.

Hard disk controller 122 generally represents the portion of processingunit 120 configured to manage the transfer of blocks of data to and fromhost interface unit 136 and read/write data channel unit 118. Hard diskcontroller 122 can be configured to perform operations to manage databuffering and to interface with host interface unit 136, according to adefined computer bus protocol, as described above. For example, harddisk controller 122 can receive and parse packets of data from hostinterface unit 136. Further, hard disk controller 122 is configured tocommunicate with a host, such as a host computer or the like. Forexample, hard disk controller 122 may be configured to report errors tohost and format disk 102 based on commands received from host. In otherembodiments, the host merely sends write commands and read commands tothe disk drive via the host interface unit 136 and the hard diskcontroller 122 handles formatting the disk and completing the read andwrite commands. The host interface unit 136 can include a read and writechannel for encoding and decoding information representing data,performing error corrections on the data, and the like.

Disk 102 includes a stack of one or more disks having magnetic materialdeposited on one or both sides thereof. Disk 102 may be composed of alight aluminum alloy, ceramic/glass, or other suitable substrate thatmagnetic material may be deposited thereon. Using electromagnetictechniques, data may be stored on disk 102 by orientating an area of themagnetic material. Data stored on disk 102 may be organized as datablocks. Data blocks are typically 512 bytes or 4 kilobytes (4 KB) insize, but may be other sizes as well. The magnetic areas of disk 102 maybe arranged into a set of radially spaced concentric tracks, illustratedin FIG. 1 as N−1, N, and N+1. A particular data block may be locatedwithin a portion of a particular track.

Magnetic material of disk 102 is configured according to one of aplurality of magnetic recording techniques. Examples of magneticrecording techniques include longitudinal magnetic recording (LMR) andperpendicular magnetic recording (PMR). Additional magnetic recordingtechniques include shingled magnetic recording (SMR) and heat assistedmagnetic recording (HAMR). SMR is a type of PMR that increases bitdensity compared to PMR by allowing previously written tracks to bepartially overwritten. In other words, the write head overlaps apreviously written track and erases a portion of the previously writtentrack. The result is a thinner track and a disk drive having a highertrack pitch or increased track density. The previous tracks arepartially overlapped, similar to shingles on a roof and hence the nameshingled magnetic recording. HAMR may be used in conjunction with LMR,PMR, or SMR techniques to achieve higher areal storage density.

The bit density, distance between tracks (referred to as track pitch),and track density of disk 102 may vary according to a magnetic recordingtechnique. Track density may be defined according to the number oftracks per radial length (e.g., track per inch (TPI). Track pitch may bedefined as a target or nominal distance between tracks. Further, asillustrated in FIG. 1, disk 102 is configured to include plurality ofregions, i.e., R0, and R1. Data may be recorded to each of R0 and R1using different track densities and track pitches. Data can also berecorded using different writing techniques. In addition, certain typesof data can also be compressed. For example, video data can becompressed as, upon being read, smoothing techniques can be used in theevent of errors occurring in the information as read from the disk ormagnetic layer of the disk.

FIG. 2 is a schematic diagram illustrating an example of a plurality ofregions on the surface or surfaces of one or more disks 102 in a diskdrive, according to an example embodiment. As shown in FIG. 2, the disksurface or surfaces include a number of regions 210, 220, 230, 240, 250and 260. As described above, a region may include a plurality of sectorswhich are contained in a plurality of tracks associated with the region.The region can be defined according to a number of radially adjacenttracks, or as a range of radially adjacent tracks that are at a range ofradial distances from the center of the disk. The region can also bedefined as a number of physical block addresses or even as a number oflogical block addresses, which will be discussed in more detail below.

The regions 210, 220, 230, 240, 250 and 260 include a plurality ofI-regions 210, 220, 230, 240 and 250 where data is written. As shown,I-regions 210, 220, and 240 are written as shingled magnetic recordingwith write verify (SMR w/Write Verify). Some of these may be writtenfrom an innermost radius to an outermost radius of the region, whileothers may be written from the outermost radius to the innermost radiusof the region. I-region 230 is written as iPMR which is an I-regionwritten using indirected perpendicular magnetic recording. This is notshingled or does not have tracks which overlay one another. The trackwidth of the iPMR I-region 230 will be wider than the SMR regions. Thedata is indirected which means that the host gives write commands usinglogical block addresses and the drive converts those to a physical blockaddresses. This is described in further detail below. The track widthswill be closer to the write width of the write element of thetransducer. I-region 250 is banded SMR. This is shingled magneticrecording. Bands are written near or at the innermost radius and at ornear the outermost radius of the I-region 250. Although not shown inFIG. 2, an I-region can be written as autonomous SMR. Autonomous SMR isthe host is oblivious to the SMR write constraints. The Host can sendwhatever read/write commands it wants to the drive. The drive handlesall the defrag operations.

The regions can also include an E-region 260 where data is writtentemporarily until being rewritten to an I-region. In one exampleembodiment, the E-region is an on disk cache. The E-region 260 is alsoreferred to as an “exception region” or a write buffer area or E-cache.An E-region 260 is used as a staging area for data or informationrepresentative of data which will ultimately be written to an I-region.An E-region may be configured to have either shingled or unshingledtracks. It should be noted that in some examples, hard disk drive 100may include a so-called hybrid E-region where a hybrid E-region includesareas of disk 102 and a portion of data SRAM 130 which may be used byhard disk drive 100 for data staging. In another embodiment, the hybridE-region can also include NAND memory. Generally, only a minor portionof a disk's area (e. g., 1%-10%) is an E-region 260. It should be notedthat the I-regions 210, 220, 230, 240 and 250 can be associated with onedisk surface or can be associated with several disk surfaces on severaldisks. In addition, an E-region 260 can be associated with one disksurface or with several. In one embodiment, there may be one E-regionper major surface of the disk drive 100. In still other embodiments, theE-region can be expanded or contracted dependent on the need for a cacheregion. Further, it should be noted that although not shown, disk 102may include other types of regions including, for example, guard regionsand write-twice cache regions. It should be noted that other types ofmagnetic recording techniques may incorporate techniques that allocateareas of a disk to be used as a write buffer area. Thus, disk 102 may beconfigured according to any combination of magnetic recording techniques

As described above, data stored on disk 102 may be organized as datablocks. In some example embodiments, the disk drive can use addressindirection to write blocks of data to disk 102. That is, host filesystems deal with logical block addresses (LBAs) in commands to writeblocks of data to disk 102 and read blocks of data from the disk 102without regard for actual locations on the disk. The actual physicaladdress is the physical block address (PBA) used internally by hard diskdrive 100. Address indirection is typically implemented in thecontroller portion of the drive's architecture (e. g., hard diskcontroller 122) using indirection tables which are used to keep track ofthe physical location associated with a LBA. Put another way, theindirection tables map the LBA to a PBA in the disk drive 100.

Hard disk controller 122 can perform address indirection. Whenperforming address indirection, the hard disk controller 122 translatesthe LBAs used in host commands (to write or to read informationrepresenting data) to an internal physical address, or an intermediateaddress from which a physical address can ultimately be derived. Itshould be noted that for a hard disk drive that utilizes SMR, thephysical block address (PBA) associated with a logical block address(LBA) can change frequently. Further, for an SMR hard disk drive, theLBA-PBA mapping can change with every write operation because the harddisk drive may dynamically determine the physical location on the diskwhere the data for an LBA will be written. Further, the data for thesame LBA may be written to a different location the next time the hostLBA is updated. In addition, a hard disk drive, such as hard disk drive100, may autonomously move data between write caches in RAM, writecaches on disk 102, E-regions on disk 102 and I-regions on disk 102. Insome examples, the LBAs for the data may stay the same regardless ofwhere the hard disk drive 100 has the data stored. Further, backgroundprocesses, such as, for example, defragmentation may also be executedautonomously by hard disk drive 100 to move data sectors from one PBA toanother while the LBA stays the same. Thus, hard disk drive 102 may beconfigured to use address indirection in association with multiple typesof write operations.

Interface processor 124 generally represents the portion of processingunit 120 configured to interface between servo processor 126 and harddisk controller 122. Interface processor 124 may perform predictivefailure analysis (PFA) algorithms, data recovery procedures, report andlog errors, perform rotational positioning ordering (RPO) and performcommand queuing. In one example, interface processor may be an ARM®processor.

As described above, data is typically written to or read from disk 102in blocks or sectors contained on a track of a disk drive. The blocksizes can be 256 bytes or 4096 bytes, in some embodiments. Disk 102 mayalso include one or more servo wedges that extend radially across thetracks of the disk. These wedges contain servo sectors and arecircumferentially or angularly-spaced and are used to generate servosignals. A servo signal is a signal read from disk 102 that may be usedto align slider 106 with a particular sector or track of disk 102.Server processor 126 generally represents the portion of processing unit120 configured to control the operation of voice coil motor assembly 110to insure slider 106 is properly positioned with respect to disk 102.Servo processor 126 may be referred to as a Servo Hardware AssistReal-time Processor (SHARP). Servo processor 126 may be configured toprovide closed loop control for any and all combinations of: sliderposition on track, slider seeking, slider settling, spindle start, andspindle speed. Further, servo processor 126 may include a set ofinstructions to calculate servo related variables.

For example, a servo signal read from disk 102 may be used by servoprocessor 126 to determine the amount of displacement of slider 106 fromthe center of a track. The value of this displacement may be referred toas run out. The value of this displacement may also be referred to asthe position error signal (PES). Run out may include repeatable run out(RRO) caused by spindle assembly, or non-repeatable run out (NRRO)caused by internal or external vibrations. Run out is one example of aposition accuracy associated with a read or write included in slider106. If a measured value of NRRO is greater than a predeterminedthreshold, a write operation may be inhibited. This threshold may bereferred to as write inhibit slice (Winh) In addition to servo signals,sensors such as vibration measurement unit 138 may provide informationto servo processor 126 and/or processing unit 120 that allow processingunit 120 to calculate a position accuracy value associated with a headof slider 106. Vibration measurement unit 138 may be any deviceconfigured to measure vibration of hard disk drive 100 and/or disk 102and provide a measurement to processing unit 120. In one example,vibration measurement unit 138 may include an accelerometer, or thelike.

FIG. 3 is a block diagram illustrating an example error correction unit300 that may utilize techniques described in this disclosure. In theexample illustrated in FIG. 3, error correction unit 300 is configuredto receive a servo signal and/or a vibration measurement signal andoutput a physical address in conjunction with receiving a write command.The physical address corresponds to a location of a sector within atrack on a disk surface. Of course, the track will be associated withone of the regions 210, 220, 230, 240, 250 or 260 of the disk or disks.As described above, address indirection may be used to map a logicaladdress to a physical block address or physical address. It should benoted that although error correction unit 300 is illustrated as havingdistinct functional blocks, such an illustration is for descriptivepurposes and does not limit error correction unit 300 to a particularhardware architecture. Functions of error correction unit 300 may berealized using any combination of hardware, firmware and/or softwareimplementations. In one example, error correction unit 300 may beimplemented as part of processing unit 120. Further, each component oferror correction unit 300 may be included as part of hard diskcontroller 122, interface processor 124, and/or servo processor 126.

As illustrated in FIG. 3, error correction unit 300 includes servodecode unit 302, run out calculator 304, track density calculator 306,and zone format selector 308. As described above, the disk 102 has servosectors which may be used to generate servo signals. Servo decode unit302 may be configured to decode a servo signal read from a disk, such asdisk 102, and determine a position of a read head and/or a write headwith respect to a servo track. A data track does not necessarilycorrespond to a servo track. The data track can have a centerline thatis offset from the centerline of a servo track. As mentioned herein, thetracks can be written with variable track pitch which means the trackcenters of the data tracks also vary. For example, the centerline of adata track depends on how much of the previous track is overwrittenduring shingled recording. The servo wedges and the servo tracks aregenerally rather precisely written. The data track may have a centerthat includes a fractional portion of a data track. In theory, the servois used to position the read head precisely over the centerline of adata track in which a physical block, such as a sector, is located. Inactuality, the servo positions near the centerline. In some disk drives,there may be as many as sixty servo wedges radiating out from the centerof the disk. Other embodiments of disk drives include disks that have400-500 servo wedges radiating out from the center of the disk. Afeedback control loop is used to keep the read element or write elementsubstantially on a centerline. The servo calculates a position errorsignal which is an amount offset from the centerline of the desiredtrack. This is used in a feedback control loop that is used to power theVCM associated with the actuator arm and keep the read head or elementsubstantially centered until the next sample can be taken at the nextservo wedge.

As illustrated in FIG. 3, servo decode unit 302 may receive a servosignal from read/write data channel unit 118. Run out calculator 304 maybe configured to receive a position error signal (PES) and calculate arun out value for a time window. In one example, a time window may beone second. In other examples, a time window may be greater or less thanone second. In addition to or as an alternative to receiving a PES, runout calculator 304 may be configured to receive a vibration measurementsignal and to calculate a run out value based at least in part on thevibration measurement signal. In one example, run out calculator 304 mayreceive a vibration measurement signal from vibration measurement unit138. Once the repeatable run out value is known it can be used to enabletrack following by a read or write element. In addition, the repeatableportion of the run out can be removed from the PES thus leaving thenonrepeatable run out (NRRO) portion. Of course, some of the NRRO can bevibrations associated with the operating environment in which the diskdrive operates. Thus, the value of the PES over time is one indicator ordetector of the favorability of the operating environment in which thedisk drive 100 is operating. Other vibration detection elements such asa vibration detection unit 138 may also be used to detect vibration.Such a vibration detection unit 138 may include one or moreaccelerometers, for example. It should be noted that there are manypossible configurations for the vibration detection unit 138. It shouldalso be noted that vibration may vary at different times. For example,if the disk drive 100 operates in an environment with loud music, thevibrations introduced may be greater than at night when there may belittle or no music. In another example, vibrations may be introduced byother disk drives in a bank of disk drives which may be associated witha data warehouse. If the other drives are not operating or shut down fora time, the operating environment will likely be more favorable to usingother writing techniques where the data capacity can be increased. Theamount of increase in the capacity of the drive will, at least in part,depend on how favorable the environment becomes.

The disk drive 100 includes at least two I-regions to which differentwriting techniques can be used for storing information representingdata. In one embodiment, the two I-regions could be on one disk or evenone disk surface. In another embodiment, the disk drive 100 couldinclude a disk 102 that has a plurality of actual disks. In thisembodiment, the two I-regions could be on the two disks. In oneI-region, perpendicular magnetic recording (PMR) or one of the types ofPMR writing techniques could be used to write data. For example, asshown in FIG. 2, the one region could be region 230 that is written withiPMR. The other I-region 240 could be written using SMR. As shown inFIG. 2, region 240 includes SMR that has been write verified. The iPMRregion would have the advantages associated with PMR. In the iPMR region230, data can be written to any track in that employs this technology.In other words, a disk drive using PMR or iPMR technology can easilyhandle random writes and generally can provide the performance of a diskdrive that only handles PMR writing technologies. The SMR region 240introduces the constraint that random writes may not be done in place.However, if the data to be written lends itself to a sequential writes,and if there is sufficient idle time to rewrite or “defrag” writes thatwere not initially written “in place”, the SMR provides a capacity boostto the drive which may approach 150% of a disk drive using straight PMRtechnology.

The disk drive 100 can also be provided with one or more E-regions, suchas E-region 260 (shown in FIG. 2). The E-region can be a region solelyon the disk 102 or disks 102 of the disk drive 100 or can be a hybridhaving a region on the disk 102 and a portion in solid state memory. TheE-region 260 is a cache for information written to the disk drive 100.The information representing data can be rewritten from the E-region 260to one of the I-regions of the disk drive 100. In some instances, thisinformation could be held in solid state memory or on the disk 102. Inother instances, this information could be held solely on the disk 102or solely on the solid state memory. At a later time, the informationrepresenting data can be written to one of the I-regions 230, 240 andremoved from the E-region 260. In reality, the portion of the E-region260 is merely designated as free space available for storing otherinformation. This portion is then overwritten.

The disk drive can also move data amongst the I-regions 210, 220, 230,240, and 250. For example, information representing data may be writtenin the iPMR region 230. If the disk drive 100 is found to be operatingin a favorable environment, the disk drive 100 can rewrite the data to aregion 210, 220, 240 that uses the SMR writing technology. In this way,the overall capacity of the disk drive 100 can be increased on the flywhile out in the field where the disk drive 100 is operating. Asmentioned above, the amount of overwrite of previously written tracksmay also be adjusted. For example, if the disk drive 100 is found to beoperating in a very favorable state with little vibration, the amount ofoverwrite can be more aggressive thereby resulting in thinner or lesswide data tracks than when the disk drive is operating in an environmentdetermined to be less favorable. Of course, to move the informationrepresenting data, there generally needs to be a sufficient amount ofidle time to allow the shingled writing operation to take place. It iscontemplated that a write command that arrives during a data move couldbe written to solid state memory during the write operation, in someembodiments, to insure the appropriate amount of idle time to completethe write operation, such as a shingled write. In other embodiments, itis contemplated that the disk drive 100 produces a signal indicatingthat it is unable to execute a write command. The shingled write ischecked, in I-regions 210, 220 and 240 with a read operation to makesure the data is readable (i.e., write verify).

In one embodiment, the disk drive 100 includes an environmental monitor,a controller and/or processing unit 120 and a writing mechanism, such asa write element in the slider 106. The controller and/or processing unit120 acts in response to an output from the environmental monitor todetermine if the data capacity of a disk drive could be increased from afirst value to a second value. The controller and/or processing unit 120determines the second increased value. The writing mechanism, controlledby the controller and/or processing unit 120, writes data to the disk102 to realize the increased data capacity of the disk drive 100. In oneembodiment, the environmental monitor includes a plurality of positionerror signals (PES) obtained from a read head or element of slider 106.More specifically, the read head or element of slider 106 reads a servopattern on the disk 102 and produces a PES. The PES indicates theposition of the read head with respect to the center of a track beingread. These are reviewed over time and certain elements are removed,such as the repeatable run out, to produce a signal that can be used todetermine how closely the read element is following a track. The moreclosely the read/write head of slider 106 follows the track as depictedby the PES, the more favorable the operating environment of the diskdrive. Operating in a more favorable environment is conducive toincreases in the capacity of a region or regions of the disk drive. Inanother embodiment, the environmental monitor is a soft error rateobtained from a read channel of the disk drive. When informationrepresenting data is read, there may be errors. Error correction codesare used to correct the errors as the data is read. The rate of theerrors is another indication of a favorable environment. In still otherembodiments, the environmental monitor includes an accelerometer, avibration detector or the like.

A host computer 150, as mentioned above, issues write commands. The hostcomputer can issue a command to write to logical block addresses. Thedisk drive can also take the command and place the information to bewritten at logical block addresses. The logical block addressesgenerally stay the same. The actual place where data is stored is at aphysical block address. The disk drive may move data to another physicalblock address in the drive. The logical block address stays the same.The disk drive 100 and, more precisely the processing unit 120 and itsassociated memory 130 includes a table for mapping a plurality oflogical blocks that correspond to a plurality of physical blocks of dataon the disk drive. The disk drive 100 maintains the table that maps thelogical block addresses to the physical block addresses. In oneembodiment, the number of logical block addresses and physical blocksare initially set at a factory, to hold a first amount of data. Theplurality of logical block addresses have a starting logical blockaddress and an ending logical block address with the first value being afactory setting. The ending logical block address is increased to asecond value greater than the first factory setting value by thecontroller 120 in response to an input from the controller 120. A hostcomputer will query the disk drive 100 as to the ending logical blockaddress after it has written to a portion or region of the disk 120. Ifthe disk drive 100 was able to write more data than the original factorysetting value it will return a new ending logical block address. Theending logical block address is increased to the second value greaterthan the first factory setting value by the controller 120 in responseto an indication from the environmental monitor that the disk drive wasoperating in a favorable environment, such as an environment which wouldallow writing additional data to the region 210, 220, 230, 240, 250 andto disk 120. In one embodiment, the ending logical block address isincreased to the second greater value in response to a write verify of aset of data on the disk 120. The write verify is a read operation thatverifies all that has been written is readable.

In another embodiment, the disk drive 100 includes at least a portion ofthe disk, such as region 210, 220, 230, 240, or 250 of a disk drive 100having an area with a factory set logical block start address and afactory set logical block end address. The disk drive 100 also includesa writing mechanism, such as a write element in the slider 106, forwriting information to the disk, and a reading element, such as a readelement in the slider 106, for reading information from tracks on thedisk 102. The disk drive 100 also includes an apparatus for producing aposition error signal depicting the distance between the read elementand the center of a track on the disk, such as the servo patterns and amemory of the track center of a particular track. The disk drive alsoincludes a controller 120 that controls many aspects of the disk drive100, including the reading element and the writing mechanism.

The controller 120 includes a microprocessor that executes instructionsin instruction SRAM 128 to cause to cause the read element to monitorthe position error signal to determine when the disk drive is in afavorable environment. The instructions in instruction SRAM 128 causethe write element to write a first set of tracks having a first widthand read the first set of tracks, and to write a second set of trackshaving a second width, narrower than the first width. The read element,associated with the slider 106, reads the second set of tracks. Thecontroller 120 also resets the factory set logical block end address toa higher value in response to reading the second set of tracks. In oneembodiment, the second set of tracks has a second width written so thatthe errors in the information being read can be corrected on the fly. Inanother embodiment, the second width (for the second set of tracks) iswritten so that the errors in the information as read occur at a ratethat can be corrected. In still other embodiments, the second width (forthe second set of tracks) is written so that the error rate is less thana threshold error rate value. In some other embodiments, the secondwidth (for the second set of tracks) is written so that the errors inthe information being read are at a soft error rate less than athreshold value.

FIG. 4 is a flow diagram of a method 400 for increasing the datacapacity of a disk drive from the factory settings for data capacity,according to an example embodiment. The method 400 includes determiningif the disk drive is in a favorable or stable environment (410), writingdata to at least one portion of the disk drive at a higher capacity thanthe factory setting for the at least one portion of the disk drive(412), and in response to a determination of a favorable or stableenvironment, resetting the capacity for at least one portion of the diskdrive (414). Determining if the disk drive is in a stable or favorableenvironment (410) includes reviewing feedback from a read element of thedisk drive, or reviewing a position of a read element with respect to acenter of a written track on the disk drive. The method 400 can alsoinclude monitoring the error rate by reading previously writteninformation. Resetting the capacity for at least one portion of the diskdrive (414) includes increasing the number of logical block addressesfor storage of information to a higher number than the number set at afactory or set at manufacture. This is done out in the field or in theenvironment where the disk drive operates on a day to day basis. In oneembodiment, writing data to at least one portion of the disk drive, suchas a region 210, 220, 230, 240, 250 at a higher capacity than thefactory setting for the at least one portion of the disk drive includessqueezing the tracks closer together in the at least one portion of thedisk drive 100. In some embodiments, the method 400 also includesreading the information representing data to verify that the writteninformation can be read. In still further embodiments, the method 400includes compressing data as written. It should be noted that a diskdrive could have one region or could have multiple regions.

FIG. 5 is a flow diagram of another method 500 for increasing the datacapacity of a disk drive from the factory settings for data capacity,according to an example embodiment. The method 500 includes splitting ahard disk drive with a fixed maximum number of LBAs into a plurality ormultiple regions (510). Each region is provided with its own fixedStart-LBA and End-LBA (512). An initial minimum number of LBAs in eachregion are allocated for writing (514). Each region would, thus have alast writeable LBA which was less than the max LBA associated with theregion. As user data is written to a region, the hard drive canrecalculate the minimum number of LBAs allocated for writing (thusrecalculating the last writeable LBA for that region) (516). It shouldbe noted that as data is further compressed or as the tracks are furthersqueezed, more LBAs are available to hold information related to userdata. In short, the more the data tracks are squeezed together or themore the data is compressed, the more information can be written to aregion. Generally, the calculations for the last writeable LBA in aregion assume a worst case scenario or worst case environment, such thatno further compression or squeezing could take place to make furtherspace available.

FIG. 6 is a schematic diagram showing physical regions 610, 612, 614,616, 618 of a disk drive that have a plurality of tracks that include aplurality of physical block addresses, and which include a plurality ofgroupings of logical block addresses 620, 622, 624, 626, 628 whichcorrespond to the regions 610, 612, 614, 616, 618, according to anexample embodiment. The disk drive is divided into regions 610, 612,614, 616, 618 which will include physical block addresses. The regions610, 612, 614, 616, 618 are physical regions on the disk 102 (shown inFIG. 1). It should be noted that the regions 610, 612, 614, 616, 618 canbe on one major surface of a single disk or on several disks in a diskstack. In one embodiment, each of the regions is given a startinglogical block address, an ending logical block address, and a maximumlogical block address. The max LBA is fixed for the life of the device.The max LBA generally represents 3-4 times the physical iPMR capacity.The region start LBAs are also fixed for the life of the device. In oneembodiment, the LBAs are mapped linearly to physical regions in an outerdiameter (OD) to inner diameter (ID) fashion to maintain expectationthat lower LBAs have higher data rates. As shown in FIG. 6, the physicalblock addresses correspond to 256-megabyte (256 MB) physical iPMRregions 610, 612, 614, 616, 618. The physical regions 610, 612, 614,616, 618 are represented by LBAs 620, 622, 624, 626, 628 that allow 1 GBof logical space per region. The extra space allows for gains in thePBAs from standard iPMR when the information is written using analternative writing technique, such as SMR, Write Verify, Dynamic TrackSqueeze and Compression. The LBA max and LBA min are set for life at thetime of manufacture. At the factory or at time of manufacture, an LBAend which is between the LBA min and LBA max is set. In the exampleshown in FIG. 6, the LBA end is set so if all the LBAs were filled usingan iPMR writing technique, the PBA corresponding to the LBA would befilled with 256-kilobytes (256 KB) of data. This is a worst casescenario. Of course, the PBA can be written so that more data can bestored in the physical space associated with the PBA. This isaccomplished by determining that the disk drive 100 (FIG. 1) isoperating in an environment exhibiting favorable conditions and writingusing another technique. The amount of user data that can be written toa region 610, 612, 614, 616, 618 is unknown initially and remains onlyan estimate until the region is actually completely filled with userdata. In operation, the region is used for storing data until the endLBA is reached. The host computer then queries or polls the disk driveas to whether additional space is available. If available, the diskdrive responds with a new LBA end value. The additional space can thenbe allocated by the host for new write operations. It should be notedthat some regions may have larger physical regions associated with them(esp. regions positioned near the OD). In other embodiments, multiplephysical regions are mapped to one logical region.

The size of the regions 610, 612, 614, 616, 618 can be varied or can beof the same size. In one example embodiment, the regions 610, 612, 614,616, 618 are of equal maximum LBA size. In another embodiment, multipleregions of equal size can be combined in one or used as part of one LBA.In another embodiment, the regions are of unequal size. In anotherembodiment, Max-LBA is three to four times the physical iPMR datacapacity to allow for gains from other magnetic writing techniques, suchas SMR, SMR with write verify, track squeeze, compression, or the like.In some embodiments, the LBAs are mapped from OD to ID (e.g., lower LBAshave higher data rates). The host 150 stores current parameters of harddisk drive 100, and in other embodiments the host 150 can poll the harddrive 100 for its current parameters.

A computer system includes a host 150 and a disk drive apparatus 100communicatively coupled to the host 150. The disk drive 100 includes atleast one disk 102 having two major surfaces divided into a plurality ofregions 610, 612, 614, 616, 618, as shown in FIG. 6. LBAs 620, 622, 624,626, 628 are associated with the regions 610, 612, 614, 616, 618. Theregions 610, 612, 614, 616, 618 include a start logical block addressand a maximum logical block address. The host 150 sets a region asallocated and requests the last logical block address (end LBA) for theregion 610, 612, 614, 616, 618. The host 150 frees the allocation up tothe last logical block address (end LBA) in response to the disk drivereturning the last logical block address (new end LBA), and after thelast logical block address is consumed, the host requests the lastlogical block address again. The host, in response to receiving anincreased end logical block address indication for a region, frees thespace associated with the region between the increased end logical blockaddress and the previous end logical block address. The host 150 issueswrite commands and read commands to the disk drive 100. The writecommand is for storing information representing data to a disk surface102 within the disk drive 100. The read command is for retrievinginformation representing data from a disk surface 102. In oneembodiment, the host 150 provides an indication of a type of dataassociated with a write command. The write element, associated with theslider 106, is positioned by the controller 120 to overwrite at least aportion of a previously written track in the second region, in someembodiments. In still some other embodiments, the host 150 compressessome types of data. When compressed data is written to a region of thedisk drive it effectively increases the data density and capacity of thedisk drive. When compressed, there is less information representing datafor a given amount of data when compared to uncompressed data.Accordingly, when compressed, the information representing the datatakes up less space. Therefore, there is more space available afterwriting compressed data to a PBA.

In one embodiment, the disk drive 100 includes an E-region, such asE-region 260 in FIG. 2. The disk drive 100 writes informationrepresenting data to the E-region 260 and returns a write completeresponse to the host 150. In some instances, the disk drive 100initially writes information representing data associated with a writecommand to the E-region 260, and moves the information representing datafrom the E-region 260 to at least one of the plurality of I-regions 210,220, 230, 240, 250 during an idle time of the disk drive 100. The diskdrive may use a plurality of write methods for writing informationrepresenting data to the plurality of I-regions of the disk drive 100. Adefault write type is perpendicular magnetic recording.

A disk drive 100 has at least one disk 102 with at least two major disksurfaces comprising a first I-region 210 having a first maximum logicalblock address, a second I-region 220 having a second maximum logicalblock address, and an E-region 260. In one embodiment, informationrepresenting data is initially written to the E-region. The informationrepresenting data is read and written to at least one of the firstI-region or the second I-region. In another embodiment, the informationrepresenting data is written directly and sequentially into the firstI-region and the second I-region. In some embodiments, the informationwritten to the first I-region 210 is written using a first method andthe information written to the second I-region 220 is written using asecond method. One of the first or the second region includes aplurality of tracks written using perpendicular magnetic recording. Theother of the first or the second region includes a plurality of trackswritten using shingled perpendicular magnetic recording. In anotherembodiment, the other of the first or the second region includes aplurality of tracks written using shingled perpendicular magneticrecording with write verify. In some embodiments, the other of the firstor the second region includes a first band near the innermost diameterof the other of the first or the second region and a second band nearthe innermost diameter of the other of the first or the second region.In still another embodiment, the other region includes a plurality oftracks written after compressing the information representing data.

The disk drive 100 includes physical block addresses where data isstored. The physical block address relates to the actual physicaladdress of a set of data. In actuality, a set of logical block addressesare assigned to a set of physical block addresses that make up a region.The logical block addresses are then associated with the actual locationof the data. A table is kept of the logical block addresses of the dataand its associated actual location in physical block addresses. Attimes, the data may be moved. The logical block address associated withthe data stays the same despite a new physical block address. The diskdrive 100 includes a table which is changed to reflect current PBA forthe data associated with a LBA. The disk drive 100, it is said, includeslogical block addresses which are mapped to physical block addresses. Atleast one of the first end logical block address or the second endlogical block address is reset to a value higher than the at least oneof the first end logical block address or the second end logical blockaddress after writing to at least a portion of the first region or thesecond region, respectively. In other words, the regions can be writtenso as to hold more data than originally designed to hold.

In many instances, the data capacity is designed to a less than perfectcase scenario. The conditions where a disk drive operates can, manytimes, be more favorable than the design point. When a favorablecondition or conditions are detected, the write operations can becontrolled to write data that will have increased capacity. Of course,in other embodiments, the conditions may be even worse than the designpoint. In this case, the capacity of the disk drive could be decreased.The reset first end logical block address or the reset second endlogical block address reflects an increase in the capacity of at leastone of the first I-region or the second I-region. The increase incapacity results from the method for writing to the respective I-region.The disk drive 100 further includes a controller 120 for determining theincrease in capacity for the respective I-region. The controller 120monitors the disk drive 100 for conditions favorable to writing at anincreased capacity. The controller 120 also determines the write methodto use to increase capacity. The controller 120 also determines when thedrive is likely to be idle for a period of time so that it can performwrites that may take longer to complete during the idle times. In someembodiments, history of usage of the drive is maintained in the diskdrive 100 so that idle times can be predicted. In some embodiments, adisk drive 100 has a plurality of disks which have two major surfacesfor storing information for storing data. In some embodiments, the firstI-region is located on one disk and the second I-region is located onanother disk in the disk drive.

FIGS. 7 A, 7B and 7C show a disk 102 of a disk drive that includesvarious embodiments for RPM multiplication, according to another exampleembodiment. FIG. 7 A shows a disk 102 of a disk drive that has radialcopies of information representing data, according to an exampleembodiment. In this embodiment, substantially the same informationrepresenting data is written in the first I-region 710 and the secondI-region 720 on the disk 102. The first I-region 710 and the secondI-region 720 are located at different radial distances from the centerof the drive. In some embodiments, the first I-region 710 and the secondI-region 720 are located on different surfaces of the disk and thereforeunder different sliders and read elements. This technique allows forshorter seeks and faster recovery of information representing data whenwritten at two different radial positions with respect to the center ofthe disks. As shown in FIG. 7A, the first I-region 710 is further fromthe slider and the read element housed therein than the second I-region720. Therefore, data in the first I-region 710 and the second I-region720 are located at different distances from the actuator arm 108 andfrom the slider 106 attached thereto. When a read command is issued, thedisk drive can seek to the one of the first I-region 710 and the secondI-region 720 which is closer to the slider 106 and the read elementhoused with the slider.

FIG. 7B shows a disk 102 of a disk drive that has rotational copies ofinformation 731, 732, 733, 734, 735, and 736 representing data,according to an example embodiment of RPM multiplication. FIG. 7C showsa disk 102 of a disk drive that has another embodiment of rotationalcopies of information representing data 741, 742, 743, 744, 745, 746,according to another example embodiment of RPM multiplication. The loadbeam or actuator arm and slider have been removed from FIGS. 7B and 7Cfor the sake of clarity. In each instance the rotational copies arelocated at various rotational positions around the disk 102. As shown inFIG. 7B, the areas of duplicate data are located at the same angularposition in a region closer to the inner diameter and in a region closerto the outer diameter of the disk. The data can be shifted rotationallyso that it may be closer to a slider carrying a read element at anygiven time. FIG. 7C shows rotational copies located around the disk 102.The areas 741, 742 and 743 are offset from the areas 744, 745, and 746.The areas can be paired in any way in which one area 741 may have a copyof the data at 746, for example. The areas 731, 732, 733, 734, 735, and736 could also be carrying the same data.

FIG. 8 is a schematic diagram showing a disk 802 that uses bandedrecording, according to an example embodiment. A disk drive includes thedisk 802, which can be a single disk or which can be a stack of disks.The disk 802 includes a first I-region 820, a second I-region 830, and athird I-region 840. The disk 802 also includes a first guard band 810and a second guard band 812. The guard bands 812 and 810 isolate thethird I-region 840 from the second I-region 830, and the first I-region820 from the second I-region 830. The guard bands 810, 812 provide anextra spacing between the tracks located in the second I-region 830 andthe adjacent first and third I-regions 820, 840. The guard bands 810,812 are placed between I-regions of the disk so that the second I-region830, if written with shingled magnetic recording, can be defragged whilemaintaining the shingling constraints. Of course a guard band 810, 812does not hold data or information representing data and therefore thegoal is to minimize the size of the guard band 810, 812. When adjacentI-regions, such as the second and third I-regions 830 and 840, arewritten with very thin tracks, such as those produced by shingledmagnetic recording, they tend to be more prone to far track interference(FTI). This becomes more pronounced when one of the I-regions isdefragged a number of times. In order to minimize FTI, the tracks nearguard band are written wider than the other tracks in the I-region. Asshown in FIG. 8, the second I-region 830 includes a multiplicity oftracks. Tracks 831 and 839 are wider or have a greater width than thetracks 833 between tracks 831 and 839. This reduces problems associatedwith FTI, such as partial erasure of tracks in the adjacent first andthird I-regions 820, 840.

In one example embodiment, a region, such as the second I-region 830, isbounded by the first guard band 810 to isolate the second I-region 830from the first I-region 820. The disk 802 has a major disk surface thatincludes the second I-region 830 including tracks 833 having a firsttrack width and track 839 having a second track width. The second trackwidth (of track 839) is wider than the first track width (of tracks833). The disk 802 also has a third I-region 840 including track 841having a third track width and tracks 843 having a fourth track width.The third track width is wider than the fourth track width. A guard band812 is positioned between the second I-region 830 and the third I-region840. The track 839 and the track 841 are positioned adjacent the guardband 812. The disk 802 also includes the first I-region 820 thatincludes a plurality of tracks 823 between a track 821 and a track 829.The third I-region 840 also includes a plurality of tracks between thetrack 841 and a track 849. The tracks of the second I-region 830positioned near the track 839 have track widths that are wider than thetracks positioned near the track 831, and the tracks of the thirdI-region 840 positioned near the track 849 have track widths that arewider than the tracks positioned near the track 841. In one embodiment,the tracks between the first track, such as track 831, and the secondtrack, such as track 839, have increasing track widths from the firsttrack to the second track. In another embodiment, the track widths of aplurality of tracks positioned between the first track and the secondtrack are constantly expanded. The disk drive also includes a writeelement, for writing information representing data, and a read elementfor reading information from a track on the disk. The read element andthe write element are associated with the slider 106. The disk drive 100also includes a controller 120 for controlling at least the position ofthe write element as information representing data is written to thetrack. In one embodiment, the write element is positioned by thecontroller 120 to overwrite at least a portion of a previously writtentrack in at least one of the second I-region 830 and the third I-region840. In one embodiment, the write element is dynamically controlled tooverwrite at least a portion of a previously written track in at leastone of the second I-region 830 and the third I-region 840. In otherwords, the amount of overwrite can be controlled on the fly after thedisk drive is placed in its operating environment outside the factory.The capacity of the disk drive 100 therefore can vary as a function ofthe environment in which it is located. Some environments are veryconducive to squeezing the tracks or overwriting adjacent tracks (suchas SMR) while other environments are less conducive with respect tousing these techniques. The more tightly or higher the track density,the higher the capacity of the disk drive. Using the above-describedtechnique allows the disk drive capacity to be increased in itsoperating environment after it has left the factory or manufacturingsite.

In some examples, a disk drive has at least one disk one with a majordisk surface having a first I-region 820 including tracks 823 having afirst track width and track 829 having a second track width. The secondtrack width is wider than the first track width. The disk drive 800 alsohas a second I-region 830 including track 831 having a third trackwidth, track 839 having a fourth track width and tracks 833 having afifth track width. The third track width and the fourth track width arewider than the fifth track width. The disk drive 800 also has a thirdI-region 840 including track 841 having a sixth track width, tracks 843having a seventh track width, and track 849 having an eighth width. Thesixth track width is wider than the seventh track width. The disk drive800 also includes a first guard band 810 and a second guard band 812.The first guard band 810 is positioned between the first I-region 820and the second I-region 830. The track 829 having the second track widthand the track 831 having the third track width are positioned adjacentthe first guard band 810. The second guard band 812 is positionedbetween the second region 830 and the third region 840. The track 839having the fourth track width and the track 841 having the sixth trackwidth are positioned adjacent the second guard band 812. The tracks 843having the seventh track width are positioned between the track 841having the sixth track width and the track 849 having the eighth trackwidth. The disk drive 800 also includes a write element for writinginformation representing data, and a read element for readinginformation from a track on the disk, and a controller 120 forcontrolling at least the position of the write element as informationrepresenting data is written to the track. The write element ispositioned by the controller 120 to overwrite at least a portion of apreviously written track in the second I-region 830. The write elementis dynamically controlled to overwrite at least a portion of apreviously written track in the second I-region 830.

FIG. 9 is a flow diagram of a method 900 for decreasing far trackinterference on a disk drive, according to an example embodiment. Themethod 900 includes designating a plurality of regions on a disk whereinformation is to be stored (910), separating at least two of theplurality of regions on the disk drive by a guard band (912), andwriting information representing data to at least one of the pluralityof regions (914). The information is written to one or more trackswithin the region of the disk. The track adjacent at least one of theguard bands of the region has a width greater than a track in an area inthe middle of the region. In one embodiment, writing information to thedisk in the at least one region includes overwriting at least a portionof a previously written track. The amount of overwriting is dynamicallyvariable to vary the capacity of the disk drive apparatus. The method900 also includes receiving an indication from an environmentalstability indicator (916). Writing information to the disk in the atleast one region includes overwriting at least a portion of a previouslywritten track, and the amount of overwriting in response to an outputfrom the environmental stability indicator. The amount of overwriting isdynamically variable in response to an output from the environmentalstability indicator. In one embodiment, the method 900 includes readinginformation representing data as written on the previously overwrittentrack to verify the write operation (918). In one embodiment, the methodincludes erasing the information from an E-region on the disk inresponse to verifying the write operation (920).

FIG. 10 is a flow diagram of another method 1000 for writing informationto a magnetizable disk surface on a disk drive, such as disk drive 100,according to an example embodiment. The method 1000 includes designatinga plurality of regions on a disk where information is to be stored(1010), writing information representing data to a first track in atleast one of the plurality of regions (1012), writing informationrepresenting data to a second track in the at least one of the pluralityof regions (1014), the information written to the second trackoverwriting a portion of the first track, and determining an amount ofthe first track that is overwritten based on a performance factor(1016). Determining an amount of the first track that is overwritten(1016) is done or accomplished on the fly. Determining the amount tooverwrite the track is done in the field rather than in a factory ormanufacturing facility. The method 1000 can also include conducting awrite verify on the recently written information representing data(1018). This assures that the data written can be retrieved at a laterdate. In still another embodiment, the method 1000 includes writinginformation representing data to an E-region before writing theinformation representing data to one of the plurality of designatedregions, conducting a write verify on the information representing datawritten to the one of the plurality of designated regions, and makingthe portion of the E-region that stored the verified informationavailable in response to a positive write verification. The method 1000also includes sending a write command complete signal to a source of awrite command (1020) after writing information representing data to anE-region. In another embodiment, the size of the E-region can also bechanged on the fly. The method 1000, in some embodiments, includeswriting information representing data to an E-region before writing theinformation representing data to one of the plurality of designatedregions and conducting a write verify on the information representingdata written to the one of the plurality of designated regions.

In response to a negative write verification a method 1100 isimplemented, as shown in a flow diagram of FIG. 11. An unreadablephysical block address is determined (1110), the informationrepresenting data associated with the unreadable physical block from theE-region is read (1112), and the information representing dataassociated with the unreadable physical block to the one of theplurality of designated regions is rewritten (1114). The method 1100also includes writing the information representing data associated withthe unreadable physical block at a new physical block address (1116),and mapping the new physical block address to a logical block addressassociated with an unreadable physical block (1118). In one embodiment,rewriting information representing data associated with the unreadablephysical block includes rewriting the information from the unreadablephysical block and all information written thereafter to the disk in theat least one region. In addition, the method 1100 also includesincreasing a number of logical block addresses that are available forthe at least one of the plurality of regions (1120) in response toincreasing the amount of the portion of the first track that isoverwritten by a second track.

FIG. 12 is a schematic diagram showing the transfer of data from onephysical block address or one set of physical block addresses to anotherphysical block address or another set of physical block addressesaccording to an example embodiment. As shown in FIG. 12, a physicalblock address or a set of physical block addresses is found to beunreadable or bad. This is depicted by position or area 1210 on the disk102 of the disk drive 100 (shown in FIG. 1). The arrow 1220 representsthe data being “moved” from the unreadable or bad area 1210 to a newarea which includes one or more new physical block addresses, asdepicted by area 1230. In actuality, the data is read from a cache area,such as a cache memory associated with the disk drive 100 (not shown) oran E-region 260 which is on the disk 102 of the disk drive 100. Thereare generally two options when an area is determined to be unreadableand a sequential writing method is being used on a region. In the firstoption, the unreadable portion is so marked and the physical blockaddress is marked as unreadable. The information that was to be storedthere is moved to a different position and the physical block addresscorresponding to the LBA is updated to associate the new PBA with theLBA. This is generally done when a comparatively large amount of datahas been written to the area after the unreadable portion, such as in asequential write method like shingled magnetic recording. A secondoption is to rewrite the information after the unreadable PBA. Theinformation to be stored in the unread portion and in the PBAs followingthe unread portion are retrieved and stored for rewriting. The diskdrive issues a TRIM command to indicate that all the PBAs after theunreadable portion have been made available for rewriting or effectivelytrimmed. The unreadable portion is removed and not written to. Thisportion of the disk surface will generally be marked as bad ordefective. The second option includes writing the retrieved informationto the PBAs on the disk that follow the unreadable portion.

HDD disks are generally designed to accommodate predictable vibrationscaused by normal operations. Generally, parameters are set for datacapacities of each of the regions of a disk drive when at themanufacturing site. In some embodiments, the parameters may be set for aworst case scenario when at the manufacturing site. In some instances,hard disk drives (HDD) may be subjected to vibrations caused by normaloperation of the disk drive or by ambient conditions. In otherinstances, a disk drive can be placed in a less favorable environment.For example, an HDD may be coupled to a device with speakers thatintroduce severe vibrations which can reduce the ability of a write headto accurately maintain an alignment with respect to a track of a disk.Severe vibrations may cause Track Mis-Registration (TMR) and a HDD maynot be able to perform write operations due to TMR. In still otherinstances, the disk drive can be placed in environments where theconditions are more favorable to writing data than the design pointwhich was set at a factory or manufacturing site. In other words, thedisk drive can be placed in environments where the conditions are morefavorable to writing data so that the capacity of the drive could beincreased beyond the factory settings.

The disk drive 100 is divided into regions, each of which may be one ofseveral types. These types include both PMR and SMR, but may alsoinclude other types like SMR w/write verify, banded, banded w/writeverify and RPM multiplication to name a few. The disk drive 100 candecide based on actual usage which type to use and may switch betweenthem at runtime. The extra capacity may be used internally to improveperformance or provided to the customer using dynamic variable capacitymechanisms. During idle, SMR regions (banded & auto) can be convertedinto SMR w/Write Verify regions. The extra capacity is not exposed tothe customer for this region. Autonomous regions may be written w/verifyoriginally.

FIG. 13 is a flow diagram of a method 1300 for writing information to amagnetizable disk surface on a disk drive, according to an exampleembodiment. The method 1300 includes dividing the disk surface into aplurality of regions (1310); and, for at least one region, designatingan initial logical block address (LBA) (1312), designating a minimumcapacity LBA (1314), and designating a maximum capacity LBA (1316); forthe at least one region, writing to the at least one region on the disksurface (1318); adjusting the data density based on performance factors(1320); and adjusting the capacity to a final LBA for the at least oneregion in response to the value of the adjusted data density (1322). Thefinal/end LBA will be less than the maximum capacity LBA. In oneembodiment, the plurality of regions are substantially equal in size. Inanother embodiment, the plurality of regions have at least two sizes. Inanother embodiment, writing to the at least one region includesoverwriting a portion of a previously written track within the at leastone region to form a track having a width less than a write width of awrite element. In another embodiment, writing to the at least one regionincludes shingled magnetic recording. In still another embodiment,writing to the at least one region includes perpendicular magneticrecording.

FIG. 14 is a flow diagram of a method 1400 for varying the capacity of adisk drive having information written to a magnetizable disk surface onthe disk drive, according to another example embodiment. The method 1400includes dividing the disk surface into a plurality of regions (1410);and for a plurality of regions, designating an initial logical blockaddress (LBA) (1412), designating a minimum capacity LBA for each region(1414), and designating a maximum capacity LBA for each region (1416).The method 1400 also includes writing to at least several regions of theplurality of regions on the disk surface (1418), and adjusting the datadensity based on performance factor associated with the region beingwritten (1420). Adjusting the capacity of the region to a final or endLBA for each of the regions being written to is performed in response tothe value of the adjusted data density for the region being written to.In one embodiment, the plurality of regions have at least two sizes. Inanother embodiment, writing to the at least one region of the pluralityof regions includes overwriting a portion of a previously written trackwithin the at least one region to form a track having a width less thana write width of a write element. In other embodiments, writing to atleast one of the plurality of regions includes perpendicular magneticrecording.

FIG. 15 is a schematic diagram of a physical region 1500 of a disk driveand a logical capacity of the physical region at two times T1, T2,according to an example embodiment. Initially, logical capacity of aphysical region is set to an end/final capacity which is between aminimum capacity 1510 and the maximum logical capacity 1520. In thisinstance, at time T1 the final/end capacity 1512 is located between theminimum capacity 1510 and the maximum logical capacity 1520. The minimumcapacity 1510 and the maximum logical capacity 1520 are set at thefactory or set at the time of manufacture. The initial setting of theend/final capacity at time TO is also a factory setting which accountsfor a “worst-case scenario”. Initially the disk drive 100 placesinformation representing data into the physical region 1500 until theend/final capacity 1512 is met. As mentioned above, the host 150 willquery the disk drive 100 regarding physical region 1500 after it hasreached the end/final capacity 1512. As shown, the end/final capacity1512 stopped short of the end of the physical region as depicted by thethree white rectangles shown at the bottom of the physical region 1500.As a result, the physical region 1500 has additional capacity forstoring data and returns an indication of additional capacity availableto the host 150. Also returned is an estimate of a new end/finalcapacity 1516. The host 150 or the disk drive 100 and makes this spaceavailable for storing information representing data. The host will againwrite data to the physical region 1500 until the end/final capacity 1516is reached at time T2. As shown in FIG. 15, the end/final capacity 1516is greater than the end/final capacity 1512. Information will be writtento this additional available space until the end/final capacity 1516 isfilled. Again the host will query the disk drive 100 when the end/finalcapacity 1516 is reached. If there is additional capacity available inthe physical region 1500, the end/final capacity will be adjusted onceagain. If not, the physical region 1500 will be marked as full and nomore write commands will be issued for writing within the region 1500.

In another example embodiment, the host repeats a request for the lastlogical block address upon determining that the last logical blockaddress is consumed. In other words, it is not necessary for the lastphysical block to be fully consumed before the host repeats the requestfor the end capacity of the region. The host can make the request assoon as it determines it will fill the last physical block addressassociated with a logical block address. If the disk drive has extracapacity in the region, the disk drive will answer the request with anew and increased value for the final/end LBA value. The host can thenwrite information representing data to the additional LBAs representedby the new value of the final/end LBA less the previous value of thefinal/end LBA. The new value of the final/end LBA will be less than orequal to the max LBA for the region. The new value for the final/end LBAincludes, in one embodiment, an estimate of the number of physical blockaddresses that the remaining portion of the region can hold.

In still another example embodiment, a disk drive having at least onedisk with at least two major disk surfaces includes a first I-regionhaving a first maximum logical block address, a second I-region having asecond maximum logical block address, and an E-region. Information canbe written temporarily to the E-region. This can be done when movinginformation representing data from one region to another. It can also bedone when the information is received from the host. In someembodiments, the information written directly to the first I-region fromthe host and information may be written directly to the second I-regionfrom the host. In many cases, the information is written to the firstI-region using a first writing method, and is written to the secondI-region using a second method.

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over, as oneor more instructions or code, a computer-readable medium and executed bya hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise random access memory (RAM), read-only memory (ROM),electrically erasable programmable read-only memory (EEPROM), compactdisc read-only memory (CD-ROM) or other optical disk storage, magneticdisk storage, or other magnetic storage devices, flash memory, or anyother medium that can be used to store desired program code in the formof instructions or data structures and that can be accessed by acomputer. Also, any connection is properly termed a computer-readablemedium. For example, if instructions are transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.It should be understood, however, that computer-readable storage mediaand data storage media do not include connections, carrier waves,signals, or other transient media, but are instead directed tonon-transient, tangible storage media. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and BLU-RAY® disc, where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e. g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that the specificdetails are not required in order to practice the invention. Thus, theforegoing descriptions of specific embodiments of the present inventionare presented for purposes of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed. It will be apparent to one of ordinary skill in the art thatmany modifications and variations are possible in view of the aboveteachings.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

While the embodiments have been described in terms of several particularembodiments, there are alterations, permutations, and equivalents, whichfall within the scope of these general concepts. It should also be notedthat there are many alternative ways of implementing the methods andapparatuses of the present embodiments. It is therefore intended thatthe following appended claims be interpreted as including all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the described embodiments. These and other exampleembodiments are within the scope of the following claims.

What is claimed:
 1. A disk drive comprising: a controller; anenvironmental monitor; and at least one disk with two major surfaces,wherein the at least one disk comprises: a first I-region having afirst, factory set final logical block address; and a second I-regionhaving a second, factory set final logical block address; wherein thecontroller is configured to: cause information to be written to thefirst I-region using a first type of magnetic recording, causeinformation to be written to the second I-region using a second type ofmagnetic recording, receive an indication from the environmentalmonitor, determine, based at least in part on the indication, that acapacity of at least one of the first I-region or the second I-regionmay be increased to more than an original factory setting capacity, andin response to determining that the capacity of the at least one of thefirst I-region or the second I-region may be increased to more than theoriginal factory setting capacity, reset at least one of the first,factory set final logical block address or the second, factory set finallogical block address to a final logical block address value higher thanthe at least one of the first, factory set final logical block addressor the second, factory set final logical block address, respectively, toincrease the capacity of the at least one of the first I-region or thesecond I-region to more than the original factory setting capacity. 2.The disk drive of claim 1, wherein one of the first I-region or thesecond I-region includes a plurality of tracks written usingperpendicular magnetic recording.
 3. The disk drive of claim 2, whereinthe other of the first I-region or the second I-region includes aplurality of tracks written using shingled perpendicular magneticrecording.
 4. The disk drive of claim 2, wherein the other of the firstI-region or the second I-region includes a plurality of tracks writtenusing shingled perpendicular magnetic recording with write verify. 5.The disk drive of claim 2, wherein the other of the first I-region orthe second I-region includes a first band near the innermost diameter ofthe other of the first I-region or the second I-region and a second bandnear the outermost diameter of the other of the first I-region or thesecond I-region.
 6. The disk drive of claim 2, wherein the other of thefirst I-region or the second I-region includes a plurality of trackswritten after compressing the information representing data.
 7. The diskdrive of claim 1, wherein the controller is configured to determine theincrease in the capacity of the at least one of the first I-region orthe second I-region based on the type of magnetic recording used forwriting to the at least one of the first I-region or the secondI-region, and reset the at least one of the first, factory set finallogical block address or the second, factory set final logical blockaddress to the final logical block address value higher than the atleast one of the first, factory set final logical block address or thesecond, factory set final logical block address based on the increase incapacity.
 8. The disk drive of claim 1, wherein the disk drive comprisesa plurality of disks, each respective disk of the plurality of diskshaving two major surfaces for storing data, wherein the first I-regionis located on a first disk of the plurality of disks and the secondI-region is located on a second disk of the plurality of disks.
 9. Thedisk drive of claim 1, wherein substantially the same informationrepresenting data is written in the first I-region and the secondI-region, the first I-region and the second I-region being at differentradial distances on the at least one disk.
 10. A disk drive comprising:a controller; an environmental monitor; and at least one disk with twomajor surfaces, wherein the at least one disk comprises: a firstI-region having a first, factory set final logical block address; and asecond I-region having a second, factory set final logical blockaddress, wherein information written to the first I-region is writtenusing a first type of magnetic recording and information written to thesecond I-region is written using a second type of magnetic recording;wherein the controller is configured to receive an indication from theenvironmental monitor; determine, based at least in part on theindication, that a capacity of at least one of the first I-region or thesecond I-region may be increased to more than an original factorysetting capacity; and in response to determining that the capacity ofthe at least one of the first I-region or the second I-region may beincreased to more than the original factory setting capacity, reset atleast one of the first, factory set final logical block address or thesecond, factory set final logical block address to a final logical blockaddress value higher than the at least one of the first, factory setfinal logical block address or the second, factory set final logicalblock address, respectively, to increase the capacity of the at leastone of the first I-region or the second I-region to more than theoriginal factory setting capacity.
 11. A disk drive comprising: acontroller; an environmental monitor; and at least one disk with twomajor surfaces, wherein the at least one disk comprises: a firstI-region having a first, factory set final logical block address; and asecond I-region having a second, factory set final logical blockaddress; wherein the controller is configured to: cause information tobe written to the first I-region using a first type of magneticrecording, cause information to be written to the second I-region usinga second type of magnetic recording, receive an indication from theenvironmental monitor, determine, based at least in part on theindication, that a capacity of at least one of the first I-region or thesecond I-region may be increased to more than an original factorysetting capacity, and in response to determining that the capacity ofthe at least one of the first I-region or the second I-region may beincreased to more than the original factory setting capacity, reset atleast one of the first, factory set final logical block address or thesecond, factory set final logical block address to a final logical blockaddress value higher than the at least one of the first, factory setfinal logical block address or the second, factory set final logicalblock address, respectively, to increase the capacity of the at leastone of the first I-region or the second I-region to more than theoriginal factory setting capacity after writing user data to at least aportion of the first I-region or the second I-region and withoutremoving the user data.